Pediatric pulmonology
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Pediatric pulmonology · Jan 1991
Pilot study for the development of a monitoring device for ventilated children.
Airway pressure and air flow were measured at the endotracheal tube in 13 children on a variety of ventilators. These signals were stored for analysis on a computer. Further data sets were obtained after 24 hours or following major interventions. ⋯ There was minimal interference with patient care. This pilot study demonstrates that changes in respiratory mechanics can be displayed safely and easily in ventilated patients using resistance and compliance loops. Further work is necessary to confirm the usefulness of real time of these displays.
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Pediatric pulmonology · Jan 1991
Inspiratory time and pulmonary function in mechanically ventilated babies with chronic lung disease.
To learn if increasing inspiratory time would improve pulmonary function in mechanically ventilated babies with chronic lung disease, we measured lung mechanics and alveolar ventilation at three inspiratory times: 0.4, 0.6, and 0.8 s. Nine babies were studied. Their mean birth weight was 875 g (range, 570-1,100 g), gestational age 27 (24-34) weeks, and age 7 (4-12) weeks. ⋯ At 0.6 s and 0.8 s, when compared to 0.4 s, significant increases occurred in tidal volume (10.4, 10.1, and 8.4 mL/kg, respectively), dynamic lung compliance (0.68, 0.68, and 0.53 mL/cmH2O/kg, respectively), and alveolar ventilation (6.0, 6.3, and 4.7 mL/kg/breath, respectively). Airway resistance, anatomical dead space to tidal volume ratio, and functional residual capacity were similar at the three inspiratory times. Our findings suggest that an inspiratory time greater than or equal to 0.6 s (compared to 0.4 s) increases the effectiveness of mechanical ventilation for babies with chronic lung disease.
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Pediatric pulmonology · Jan 1991
The effect of lung mechanics on gas transport during high-frequency oscillation.
With the general aim of obtaining clinically relevant information on the use of high-frequency oscillation (HFO), we examined the effects of altering oscillatory frequency (f), tidal volume (VT), and mean airway pressure (Paw) on gas exchange in rabbits, both before and after altering the animal's pulmonary mechanics by saline induced lung injury. Twenty-seven combinations of f (5, 8, 12 Hz), VT (0.5, 1, 2 mL/kg), and Paw (5, 10, 13 cm H2O) were used. Acute pulmonary injury was induced by instilling 10 mL/kg of warm saline into the lung. ⋯ VTb where the exponents a = -0.4 and b = -0.6. Our technique of a standardized saline instillation gave a reproducible and stable model of lung injury. In damaged rabbit lungs the principles of HFO appear to be similar to conventional mechanical ventilation; oxygenation depends on Paw and inspired oxygen concentration, while CO2 removal is determined by f and VT.
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Pediatric pulmonology · Jan 1991
Cold air challenge of airway reactivity in children: a correlation of transcutaneously measured oxygen tension and conventional lung functions.
For pharmacological challenges, a correlation between the induced changes of the transcutaneously measured oxygen tension (PtcO2) and of conventional pulmonary function tests (PFTs) has been documented. We performed a 4-minute cold air challenge (CACh) in 17 children with bronchial asthma under continuous monitoring of PtcO2, and correlated observed changes with CACh-induced alterations of conventional PFTs. ⋯ Changes of FVC, PEF, and Vmax50 correlated significantly as well. PtcO2 can complement or substitute for conventional PFTs in assessing the response to CACh in children.
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Pediatric pulmonology · Jan 1991
Effect of positive end-expiratory pressure on respiratory compliance in children with acute respiratory failure.
We studied the effect of positive end-expiratory pressure (PEEP) on the compliance of the respiratory system (Crs) in 25 children (age, 3 weeks to 10 years) requiring mechanical ventilation. Functional residual capacity (FRC) measurements were performed at 2 cm H2O increments, from 0 to 18 cm H2O of PEEP, and the FRC values were regressed versus PEEP. Static Crs, Crs/kg, and specific compliance (Crs/FRC) were calculated for each PEEP level. ⋯ We concluded that static respiratory compliance improves in most (but not all) children with acute respiratory failure when FRC is normalized. Static respiratory compliance reaches maximum levels at PEEP values that are close (but not equal) to those that result in FRC normalization. Thus, assessment of the effect of PEEP on compliance is required in individual patients.